Gender Dysphoria (GD) is defined as a marked incongruence between one’s experienced/expressed gender and assigned gender that the individual feels a strong desire for having the sex characteristics of the other gender. Twin studies could be helpful in making decisive conclusion on the relative role of genetics and environment on GD. Therefore, we hereby present a case of monozygotic twins with concordant female-to-male GD. Seventeen-year-old twins are introduced in this case report. The second pair attended to our clinic for psychiatric evaluation. She was suffering from GD by overwhelmed desire for having masculine features, wearing their cloths, and at the same time revolting being a girl. Although she preferred spending time with male friends, she was sexually attracted to females. Although the first pair had similar characteristics of GD, she presented apposite temperament. While temperament has been considered to be genetically inherited, the incidence of GD in our cases with different temperaments raises the question about genetic role in inheriting temperament and GD. Further twin studies will help understanding the extent of genetic influence on these features.